PRTA (Prothena) Shiller PE Ratio: (As of Sep. 16, 2026)

Prothena  (NAS:PRTA) Shiller PE Ratio Explanation

Compared with the regular PE Ratio, which works poorly for cyclical businesses, the Shiller PE Ratio smoothed out the fluctuations of profit margins during business cycles. Therefore it is more accurate in reflecting the valuation of the company.

If a company has consistent business performance, the Shiller PE Ratio should give similar results to regular PE Ratio.

Compared with the PS Ratio, the Shiller PE Ratio makes the comparison between different industries more meaningful.

Be Aware

Shiller PE Ratio assumes that over the long term, businesses and profitability revert to their means. If a company's business model does not work in the future compared with the past, Shiller PE Ratio and PS Ratio will give false valuations.

Prothena Shiller PE Ratio Related Terms

The historical data trend for Prothena's Shiller PE Ratio can be seen below:

* For Operating Data section: All numbers are indicated by the unit behind each term and all currency related amount are in USD.
* For other sections: All numbers are in millions except for per share data, ratio, and percentage. All currency related amount are indicated in the company's associated stock exchange currency.

Prothena Shiller PE Ratio Chart

Prothena Annual Data
	Trend	Dec16	Dec17	Dec18	Dec19	Dec20	Dec21	Dec22	Dec23	Dec24	Dec25
Shiller PE Ratio		Get a 7-Day Free Trial					0.00	0.00	0.00	0.00	0.00

Prothena Quarterly Data
	Sep21	Dec21	Mar22	Jun22	Sep22	Dec22	Mar23	Jun23	Sep23	Dec23	Mar24	Jun24	Sep24	Dec24	Mar25	Jun25	Sep25	Dec25	Mar26	Jun26
Shiller PE Ratio	Get a 7-Day Free Trial															0.00	0.00	0.00	0.00	0.00

PRTA vs EVMN, EDIT, CCCC: Shiller PE Ratio Comparison

For the Biotechnology subindustry, Prothena's Shiller PE Ratio, along with its competitors' market caps and Shiller PE Ratio data, can be viewed below:

* Competitive companies are chosen from companies within the same industry, with headquarter located in same country, with closest market capitalization; x-axis shows the market cap, and y-axis shows the term value; the bigger the dot, the larger the market cap. Note that "N/A" values will not show up in the chart.

Prothena Shiller PE Ratio vs Biotechnology Industry

For the Biotechnology industry and Healthcare sector, Prothena's Shiller PE Ratio distribution charts can be found below:

* The bar in red indicates where Prothena's Shiller PE Ratio falls into.

Prothena Shiller PE Ratio Calculation

For Shiller PE Ratio, the earnings of the past 10 years are inflation-adjusted and averaged. The result is used for P/E calculation. Since it looks at the average over the last 10 years, the Shiller PE Ratio is also called PE10.

The Shiller PE Ratio was first used by professor Robert Shiller to measure the valuation of the overall market. The same calculation is applied here to individual companies.

Prothena's E10 for the quarter that ended in Jun. 2026 is calculated as:

For example, Prothena's adjusted earnings per share data for the three months ended in Jun. 2026 was:

Current CPI (Jun. 2026) = 128.6700.

Prothena Quarterly Data

Add all the adjusted EPS together and divide 10 will get our E10.

Please note that we use the CPI data of the country/region where the company is headquartered. If the CPI data for that country/region is not available, then we will use the CPI data of the United States as default.

Prothena Business Description